Esters of hydroxyalkanesulfonates with alpha-sulfonated long-chain fatty acids



United States Patent G ESTERS 0F HYDROXYALKAN'ESULFONATES WITH ALPHA-SULFONA'I'ED LONG-CHAN FATTY ACIDS James K. Well, North Wales, and Raymond G. Bistline, Jr., and Alexander J. Stirton, Philadelphia, Pa, assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Application January 14, 1955, Serial No. 481,982

8 Claims. (Cl. 260-409) (Granted under Title 35, U. S. Code (1952), see. 266) R 1 OH (CH2)CHCOOCH(CH:)mSOaM souu wherein n is an integer from 9 to 19, m is an integer from 1 to 2, R is a member selected from the group consisting oi hydrogen and methyl, and M is a member selected from the group consisting of hydrogen, an alkali metal NHd, NH3(C2H4OH), NH2(C2H4OH)2 and NH (Cal-140E 3.

The esters having the formula shown above constitute a new and especially valuable family-of surface-active compounds. They are highly soluble in water and are eitective solubilizers for more difiicultly soluble surface active agents such as the sodium soaps of palmitic, stearicand longer-chain fatty acids, the long-chain alcohol sulfates and sulfonated fatty acids. These esters have the valuable property of being insensitive to dissolved salts such as are found in hard water or sea water; consequently they are especially valuable for use in compositions designed for use in such waters. They not only are'not precipitated by the salts in such water but also have a stabilizing effect on and help prevent the precipitation of soaps and other surface-active compounds that otherwise would be precipitated by such salts.

A major advantage of the esters of this invention is their extreme stability to hydrolysis in the presence of acid, base or heat.

aqueous solution to dryness,

All other esieriype surface-active.

compounds are more or less easily hydrolyzed in the presence of water, especially if heated or if in the presence of acid or alkali. There are innumerable applications in which a surface-active agent is needed that will withstand these conditions, as for instance, in metal cleaning, wool scouring, textile finishing, dyeing, mordanting, etc. For these applications, our esters are particularly suitable. The detergent properties of our esters are excellent; yet they may be greatly improved by use of conventional builders, particularly the phosphates. Thus, a highly effective detergent composition may be made from as little as one part of ester to four parts of builder. Such high tolerance of builders enables the preparation o'fwery'inexpensive, yet highly efiective detergent compositions.

; The compounds of this invention may be conveniently Chem. Soc.,

prepared by the direct esterification of the a-sulfonated fatty acid with the hydroxyalkanesulfonate:

R CHa(GH2)nCHCOOH HOHKJHDmSOaEHMI] SOaH R CH3(CH2) CH0 0 O H(CH2) mSOaHUl/I] 11 0 Neutralization of this product with an appropriate base yields the desired product. The a-sulfonated fatty acid may be prepared by any known process, as for example, the action of sulfur trioxide or chlorosulfonicacid on lauric, myristic, palmitic, stearic, behenic or similar-fatty acid. The hydroxyalkanesulfonate may also be prepared by any of several known methods, as for instance, the reaction of sulfites and bisulfites with appropriate alkylene oxides or olefinic compounds.

Since the a-sulfonated acid reagent is strongly acidic, no added catalyst is needed in making the esters. It is very helpful to conduct the esterification under conditions such that the water produced is removed from the' reaction zone as fast as formed. This may be done by use of an inert solvent that distills azeotropically with water, such as toluene, carbon tetrachloride, ethylene chloride, or the like.

Preparation of the esters of the invention is illustrated by the following examples:

EXAMPLE I Disodium Z-sulfoethyl a-sulfosterate A mixture of 0.2 g. mole each of a-sulfostearic acid and sodium isethionate and 250 ml. of toluene was refluxed, with stirring, while the water distilled azeotropically was collected continuously. .The reaction was complete after 6 hrs., at which time 6 ml. of Water had been collected. The mixture was cooled, diluted with 200 ml. of ethanol and neutralized with 18 N aqueous NaOH. Evaporation of the toluene and ethanol left 103 g. of crude product which was extracted with 400 ml. of water, leaving a small amount of the sparingly soluble sodium ,u-sulfostearic acid as a residue. After evaporating the the ester was taken up in decolorized with carbon, and twice C. The purified product thus ob- 75% aqueous ethanol, crystallized at ---15 tained in 66% yield was a white solid having the analysisshown in Table I.

EXAMPLE 11 V Disodium I-fitethyl-Z-sulfoethyl a-su lfostearate .Sodium Z-hydroxypropanesulfonate, M. P. 225 C., was prepared from 1,2-propylene oxide and sodium bisulfite by a conventional procedure [Lambert and Rose, 1949, 46-9]. This compound was then treated with a-sulfostearic acid as described in Example I to produce the desired l-methyl-Z-sultoethyl a-SlllfO- stearate. 1 i

EXAMPLE I11 Disodium 3-sulfopropyl a-sufostearate,

Allyl alcohol and a-sulfostearic acid were heated together to form allyl u-sulfostearate. The sodium salt of this compound was treated with a mixture of sodium sulfite and sodium bisulfite in the presence of oxygen to form the desired product. 'This procedure is substantially that described by Kharasch et al., I. Org.;Chem., 3-, 175-192 (1938), for sulfonating allyl alcohol.

2,806,044 a a EXAMPLES IV AND V greater than 1800 p. p. m. (as CaCOs) show the esters a can'be used in the hardest waters. 'The lime soap dis- Dzsodzum 2-sulf0ethyl a-su lfopalmltate and -behemzte parsing power values showed that by weight of the When the e-sulfostearic acid used in Example I Was eesters, based on the sodium oleate test soap, dispersed Placed with qp i r-- f h ni ci re- 5 the calcium oleate formed with hard water. The immedispectively, e p n ingfisterswereobtained. ate foam height was high. The wetting properties shown The elementary analyses of the compounds produced by sinking time indicate the esters are primarily deteriu the above examples are shown in the following table. gents rather than extremely effective wetting agents.

TABLE .I. .ANALYEESpEESTERS 0 E PLE VII ona(om),.onooodmompsoma Detergency 50mg 7 Detergency of built and unbuilt esters, compared to two well known and widely used detergents, sodium 2- Analysis Percent sulfoethyl oleate and to sodium dodecyl sulfate, was measm V R ured in hard water of 300 p. p. m. using a standard soiled cotton (A. C. H. No. 114) in a standard laboratory scale washing machine (Terg-O-Tometer). Ten swatches, 15 H 2 /2 in. x 3% in.,=we're washed in 1 liter of detergent 15 1 0H3 solution for minutes at 60 C., at 110 cycles per minf ute. Detergency was measured as AR, the increasesin 19; 1 H reflectance after washing. A difference in AR valuesof j 0.9 .was significant with at least 95% probability. Whilethe aboveexamples show the sodium salts of the disulfom'c acids, therfreeacids or the p r'a TABLE IIL-DETERGENCY 0F DISODIUM 2-SULFOETHYL alt are-ea Hy-made Thus the free a-SULFOPALMITATESAND a-SULFOSTEA'RATES acid results from the reaction .of isethionic acid with "an q-sulfo acid,.,and the.product may'then be neutralized Detergency, AR withthe appropriate alkali, ammonia or an amineto give T t M t 0 0 0 1 2 the comespqnding alts Q a etergent -y Percen The potassium salts larequite similar in properties to Dlsodmm z'suiiggihillasulfostearate 29 2 5 thesodiumsalts. Theammoniumand amine salts are even more soluble than the alkali metal salts andiingen- 34.' eral are somewhat better foaming agents; Otherwise their surface-active properties aresimilar: tothose of the 27: alkali metal salts. The salts of ethanolamine, diethanol- +005 v33 9 amine and triethanolamine are particularly desirable be- 0.025% I+0.025% IV 27.1 cause 9 their low cost and excellent surface-active sm3i9h$ii2l ifj3 23:33:: 3:: ii? 3%.? properties. 0.05% VI+0.20% A.-. 33.0 40 Sodium dodeeyl sulfate 25. Surface active properties 1 Builder A: NazSO; 71.11%. NaaPaOm 8.33, Marlo, 8.33, N8309- a 4H20 5.56. Na metasilicate 5.56, CMO 1.11. Some of the surfaceactive properties of esters of our oiaBouilder B:Na.',Pa0m55%, Nalsom, Na4Pz0110,Nametasi1lcatel0,

invention are shown in Table 'H.

TABLE'ILHSUR'FACE ACTIVE PROPERTIES OF DISODIULI Z-SULFOALKYL a-SULFO- PALMITATES .AND a-SULFOSTEARATES 'Surfaee'and Interracial ten- Product ston, 0.25% Ca Lime Soap Foam Height, Sinking Time, of salns. 1n distd. Stability, Disperstng 0.25% solns. In 0.1% 501115. in Ester. Example water 25 0., p. p. m. Power, 300 p. 111., dlstd. water 'No. dynes/crn. 0300; Percent 3 Jimmie 25 0.,

diam 11mm. 1 seconds 8. T. I. .T.

Disodium 2-sulfoethyl a-sull'opalmjtate .IV. 35.2 9. 8 1, 800 5 l 202 V 134 Disodlum 2sulfoethyl a-sulfostearate I 35. 8 11. 6 1, 890 5 23 2 Dlsodium .1-n1ethyl2 a Sulfoe a-Sulf stearate. II 46. 9: 14:5

1 B. G.'Wilkes and J. N. Wickert. lnrltEng. Chem. 29, 12344) (1937).

1H. O..Borghetty and O. AvBergman, J. Am. Oil ChGmIStS' SOOJ 27, 88-90 (1950). J. Rossand G. D. Miles, Oil-& Soap 18, 99-102 (1941).

- L. Shapiro, Am. Dyestufi Reptr. 39, 38-45, .62 (1950);

6 0.9012 5 g. dispersed the Ca soap} rmed from 0.025 g. of N a oleate.

Metallic ion stability, measured. :by the method of The detergencyof di'sodium 2-sulfoethyl a-sulostearate Harris [1. C. Harris, ASTM Bull. No. 141, 49-53. was considerably improved bybuilderA and builder B.

. The high .calcium stability values, tolerance to water of (1946)], gavevalues of 100 :for ;Mg++., Al+++, Ca++, Disodium- Z-sulfoethyl a-sulfopalmi-tate was improved by e, i, C11 Z 1 and Pb for 'disodium B, butmot by:-A;- :Mixtures of theatworestersfland IV) 2-sulfdethyl a-sulfopalmitate and disodium 2sulfoethyl responded favorably to buildingwitLA or-B.

a-sultostearate." The esters were therefore not precipi- 2-sulfoethyl oleate, withoutbuilder, ;was:not+nearl.y as

tated under the-test'conditions. a good a detergent, -at 0.l0%. concentration,.asdisodium Table H'shows that the .esterslower surface tension 2-sulfoethyl a-sulfostearateKI)jor disodium 2-sulfoethy1 and-mterfacial. tension (against a refined mineral oil). a-sulfopalmitate (IV), or a mixture of I and The presence of-builder -A improved the detergency of sodium 2-su1foethyl oleate, but the built mixture was not as good a detergent as 0.05% disodium 2-sulfoethyl u-sulfostearate+.20% A, or as 0.025% I+0.025% IV+0.20% A. Further, sodium Z-sulfoethyl oleate is not as well suited for building with the alkaline builders A or B since it is considerably more susceptible to hydrolysis in alkaline solutions than are the esters of our invention.

The two best detergent compositions of Table III are those containing 40% and of disodium 2-sulfoethyl a-sulfostearate as the active ingredient.

Washing tests with a difierent standard soiled cotton (G. D. C. No. 26) led to the same general conclusions. Disodium 1-methyl-2-sulfoethyl a-sulfostearate appeared to have detergent properties intermediate between those of disodium Z-sulfoethyl a-sulfostearate and disodium 2- sulfoethyl a-sulfopalmitate.

EXAMPLE VIII Stability .to hydrolysis in acid and alkaline solutions of the esters of our invention compared to sodium 2-su1foethyl oleate, is shown by values of the rate constants, in Table IV.

TABLE 1V.RATE OF HYDROLYSIS OF DISODIUM SULFO- S-SULFOPALMITATES AND a-SULFOSTEARATES Alkaline Acid Hydrolysis In Hydrolysis k it Disodium 1-methyl-2-sulioethyl a- 0. 13

sulfostearate (II). Disodium 2-su1foethyl a-sultopahni- 0.0051 1.0

tate (IV). Sodium 2-sulfoethy1 oleate (VI)- too rapid to measure 4. 3

accurately.

'k1=first order rate constant =%ln -i in reciprocal minutes.

kFsecond order rate constant=-: 1inliters-moles- -minutes.-

The rate of hydrolysis in acid solution was measured by heating 0.01 mole of the ester in 100 ml. of N/3 sulfuric acid at 100 C., and titrating 10 ml. samples at selected intervals. The rate of hydrolysis of disodium 2-sulfoethyl a-sulfopalmitate was found to correspond to a first order reaction and to be quite slow. In comparison, sodium 2-sulfoethyl oleate was hydrolyzed so rapidly under these conditions that the rate was not subject to accurate measurement.

The rate of alkaline hydrolysis was measured by heating 0.01 mole of the ester in 100 m1. of 0.1 N. sodium hydroxide at 100 C., and titrating 10 ml. samples at selected intervals. Alkaline hydrolysis was found to correspond to a second order reaction. Sodium 2-sulfoethyl oleate was hydrolyzed about 4 times as fast as disodium 2-sulfoethyl a-sulfopalmitate. Disodium 1-methy1-2-sulfoethyl a-sulfostearate, an ester of a secondary alcohol, was most resistant to hydrolysis. Sodium 2-sulfoethyl oleate was hydrolyzed about 33 times as fast as disodium l-methyl-Z-sulfoethyl aa-sulfostearate.

EXAMPLE The esters of our invention can be advantageously used in combinations with soap, as shown in the following washing experiments carried out as described in Example VH.

TABLE V.DETERGENCY OF BUILT COMBINATIONS OF SOAP AND DISODIUM 2-SULFOETHYL a-SULFOSTEA- RATE IN HARD WATER (300 p.p.m.)

Detergency, AR.

Total detergent concn., percent 0.05 0.10 0.25 Disodium 2-sulfoethyl asulfostearate (I)- 27. 1 29. 2 29. 7 0.10% I+.15% B 1 37. 9 0.05% I+.20% B 34. 2 0.05% I+0.05% Na pa 38. 9 Sodium palmitete 20. 8

1 Builder B: N85P3O1u 55%, NagSOt 24, NaiPzo-l 10, Na metasilicate 10, CMC 1.

EXAMPLE X The esters of our invention can be advantageously used in combination with other synthetic detergents. This behaviour is shown in washing experiments (Table VI) carried out as described in Example VH.

TABLE VI.DETERGENCY OF BUILT SYNTHETIC DE- TERGENT MIXTURES IN HARD WATER (300 P. P. M.)

Expt. Detergency, AR

Total detergent conen., percent 0. 05 0. 10 0.25 Disodium 2su1ioethyl a-sulfostesrate (I) 27. 1 29. 2 29. 7 almitate (VII) 18.8 32. 4

1 Builder A; NMSO; 71.11%, NasPaOm 3.33, N34P201 8.33, N31B03.4H20 5.56, Na metasilicate 5.56, CMC 1.11.

2 Builder B: Na5P5Ow 55%, N31SO4 24, NalPflo'l 10, Na metasilicate 10, 0M0 1.

Building with A or B markedly improved the detergency of a mixture of disodium 2-sulfoethyl a-sulfostearate and disodium a-sulfopalmitate (experiments 3, 8 and 9) to produce good detergents readily soluble in hard water.

EXAMPLE XI The esters of our invention have detergent properties in sea water. Washing experiments were carried out in the Launder-Ometer, with 1 swatch of standard soiled cotton in m1. of detergent solution, and 30 fii-inch stainless steel balls, rotating the jars at 42 R. P. M. for 30 minutes at F. Detergency was expressed as AR, the increase in reflectance after Washing. The results are shown in Table VII. The total detergent concentration was 0.25%. The synthetic sea water Was prepared as described by Vaughn et a1. [T. H. Vaughn, E. P. Hill, C. E. Smith, L. R. McCoy and I. E. Simpson, Ind. Eng. Chem. 41, 112-19 (1949)].

The esters of our invention are among the best detergents in sea water, of the list of Table VII. They form clear foaming solutions in sea water and may be built with inorganic builders or with urea.

TABLE VII-DETERGENCY IN SEA WATER [Total detergent concentration 0.25%]

Detergency, AR

Builder B: NasPaOm, 55%, NaaSOa, 24, NzuPaO 10, Na metasilicate 10, CMC 1.

We claim: 1. A compound having the formula wherein n is an integer from 9 to 19, m is an integer from 1 to 2, R is a member selected from the group consisting of hydrogen and methyl, and M is a member selected tom the group consisting of hydrogen, an alkali metal, NH4, NH3(C2H4OH), NH2(C2H4OH) a, and NH(C2H4OH)3. 

1. A COMPOUND HAVING THE FORMULA 